1. Field of the Invention
The present invention relates to modified clay sorbents which may be used as sorbents for chemical contaminants. In addition, the present invention also relates to the use of modified clay sorbents for the sorption of chemical contaminants.
2. Brief Description of Related Art
The effluents discharged from various industries, such as textile, tannery, paper, printing, food, paints, rubber and plastic, release dyes and other contaminants into the environment. Some contaminants, and/or their biodegradation products, are toxic and potentially carcinogenic. These can deleteriously affect aquatic life in water bodies and damage ecosystems.
Dye contamination of water also inhibits sunlight penetration into water and thus inhibits photosynthesis by aquatic flora. In addition, the appearance of colour in water due to presence of dye compounds may reduce its reuse potential and is also generally aesthetically undesirable.
Decolourisation of dyes which are highly soluble in water is a major problem faced by various industries. Orange II (4-(2-Hydroxy-1-naphthylazo) benzenesulfonic acid sodium) is one such dye extensively used in textile, paper, foodstuffs, hair and leather colouring. Its water solubility may reach up to 116 g/L. This dye is anionic and contains one nitrogen double bonded group (N═N) and one sulfonic acid group (NaO3S). Orange II is non-biodegradable in nature and known to induce cytogenetic changes in animals. It poses potential human health risks and is also a suspected carcinogen.
Several physical, chemical and biological processes have been developed for the removal of dyes and other contaminants in waste water. Among these processes, sorption has been proven to be an effective and attractive mechanism and clays have been used as sorbents for dyes or other contaminants in waste water. Among the clays, bentonite is the most studied material for decolourising dye waste water. Several other modified clay candidates such as pillared clay, acid treated bentonite and sepiolite, surfactant treated sepiolite, layered double hydroxides and spent activated clay have also been investigated.
However, most of the investigated natural aluminosilicate clay minerals are not suitable for the sorption of anionic and/or hydrophobic compounds, including dyes such as Orange II. As such, a need exists for clay-based sorbents which are suitable for contaminants such as anionic and/or hydrophobic contaminants, including dyes such as Orange II.
Reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in any country.